commit a8b154a637b586441bad42259a8a9b9619cd117c
author James Cowgill <james.cowgill@mips.com> Mon Nov 06 18:03:51 2017 +0000
committer Riku Voipio <riku.voipio@linaro.org> Tue Nov 07 21:58:13 2017 +0200
tree b1150b64d2df54a532dc115a472706481b4c9e5c
parent a4dd3d5172c951e05a7424f14c0f9372522b48f8

linux-user: return EINVAL from prctl(PR_*_SECCOMP)

If an application tries to install a seccomp filter using
prctl(PR_SET_SECCOMP), the filter is likely for the target instead of the host
architecture. This will probably cause qemu to be immediately killed when it
executes another syscall.

Prevent this from happening by returning EINVAL from both seccomp prctl
calls. This is the error returned by the kernel when seccomp support is
disabled.

Fixes: https://bugs.launchpad.net/qemu/+bug/1726394
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: James Cowgill <james.cowgill@mips.com>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>

linux-user/syscall.c

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 84e123b..f31b853 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -10505,6 +10505,12 @@
             break;
         }
 #endif
+        case PR_GET_SECCOMP:
+        case PR_SET_SECCOMP:
+            /* Disable seccomp to prevent the target disabling syscalls we
+             * need. */
+            ret = -TARGET_EINVAL;
+            break;
         default:
             /* Most prctl options have no pointer arguments */
             ret = get_errno(prctl(arg1, arg2, arg3, arg4, arg5));